1. Field of the Invention
The present invention generally relates to optical disk apparatuses, condition measuring methods, and condition measuring position setting methods, and more particularly, to an optical disk apparatus capable of recording a signal on an optical disk at a plurality of recording speeds, a condition measuring method, and a condition measuring position setting method.
2. Description of the Related Art
CD-Rs (compact disks-recordable) and CD-RWs (compact disks-rewritable) have respective different optimum recording powers of lasers depending on the manufacturing companies. Hence, in optical disk apparatuses for recording information on CD-Rs and CD-RWs, when a disk is loaded and a recording instruction is given, OPC (optimum power control) processing is performed. The OPC processing is for determining an optimum recording laser power and is performed by using a PCA (power calibration area) that is set in the inner tracks of an optical disk.
A description will be given of the OPC processing.
In the OPC processing, first, a predetermined signal is recorded on the PCA at a predetermined recording speed while varying the recording power of a laser in 15 stages. Next, the signal recorded on the PCA is reproduced, and 15β values are obtained from the peak values and the bottom values of a reproduced signal S1.
FIG. 1 is a graph for explaining a measuring method of the β value. In FIG. 1, V0 represents a fiducial value 0.
The β value can be obtained based on the following equation (1) where the peak value of the reproduced signal S1 is A1 and the bottom value thereof is A2.β=(A1+A2)/(A1−A2)  (1)
FIG. 2 is a graph for explaining the relationship between the recording power and the β value. In FIG. 2, the vertical axis represents the β value (β), and the horizontal axis represents the recording power (pw).
As shown in FIG. 2, the β value varies generally according to a quadratic function. A recording power pw0 at which the β value becomes the minimum is the optimum recording power.
Accordingly, the recording power pw0 at which the minimum β value is obtained among the 15 β values that are obtained based on the above equation (1) is set to the optimum recording power at the predetermined recording speed.
The optimum recording power at each recording speed is obtained by performing the above-mentioned operation for each recording speed. The obtained optimum recording powers for respective recording speeds are set to a register of a microcomputer and used when recording a signal (refer to Japanese Laid-Open Patent Application No. 2002-298356, for example).
In conventional optical disk apparatuses, the recording power has been set based on the optimum recording power that is set in the above-mentioned OPC processing, and the radius of the position on the optical disk has not been considered. Thus, there are problems in that the recording power cannot be set with accuracy, for example.